1. Field of the Invention
The present invention relates generally to devices which handle machine readable tape wound on a spool or reel, and particularly to an apparatus that efficiently packs tape onto a spool.
2. Background of the Invention
Magnetic tapes, including reel and cassette-style cartridges and other devices that use magnetic media, are used in many industries to store data, programs, and other information. Magnetic tapes are typically stored on reels or spools, which are cylinders about which the tape is wound, typically having flanges to guide the tape onto the cylinder. Accessing information from a reel or spool of tape typically requires the spool be inserted into a reading machine, which unwinds the tape from the file spool and winds it onto a temporary storage spool (also referred to as a machine reel or machine spool) until the portion of the tape with the desired information is reached. A magnetic read element reads the information, and the tape is rewound back onto the original file spool and removed from the reader.
On a typical spool holding the magnetic tape, the spacing between the upper and lower flanges of the spools (both the file spool and the machine spool) is wider than the nominal width of the tape. As the tape is fed onto these spools, the tape tends to seek either the upper or lower flange as a hard stop or guide. Since the flange spacing is wider than the tape, the tape often switches which flange it is guiding against resulting in a staggered wrap. This stagger causes two problems. First, the tape can get folded over and be damaged during shipping if one of the flanges is forced against one of the staggered wraps (for example, if the spool is dropped).
The second problem occurs in the actual tape drive. As the tape is fed from the spool with the staggered wraps across the read/write head, higher tape edge loading is required to guide the tape into a functional position with respect to the read/write element. This stagger wrap condition is aggravated during high speed rewinding of the tape due to air entrainment. Unfortunately, the flange spacing and taper is required on spools in order to account for spool run out, flange run out, file and machine reel motor elevation differences as well as the tape width tolerance itself.
Additionally, technological advancement in tape industry practices have caused tapes to be made thinner, with increasing track densities. This requires better guiding of the tape, as well as lower edge guiding forces due to the decreased thickness of the tape.
Attempts to address these problems have included a radial tracking device which physically rubs the tape and guides it onto the spool so as to reduce stagger. Such devices are complex, and result in tape wear as well as debris being introduced into the tape pack. Such devices are often large and incapable of fitting into a tape cartridge. Examples of prior art spool systems include U.S. Pat. Nos. 6,045,086 and 5,803,388.
In some prior art systems, the tape packing mechanism is direction dependent, meaning that the device works when oriented a certain way, but not in other ways. This can be a disadvantage when the same spool can be used to unload tape, but is later used to reload the tape. If the packing mechanism is direction dependent, then some re-orientation of the spool or the packing device may be required.
Therefore, the current technology would be improved by a device which guides tape onto a spool which does not wear the tape nor introduce debris, and which will fit on both the file (cartridge side) and machine reel (drive side) in a tape drive.
A tape packing mechanism is herein disclosed. In a preferred embodiment, the packing mechanism comprises a flexure (also referred to herein as a packing device) which rotates with a spool as tape is added. The flexure is pressed close to the nearest flange on the tape lead-in side by a magnet or roller or other device. The magnet or roller preferably does not rotate with the spool or reel system, therefore constantly holding the flexure nearer to the flange on the tape lead-in side as the reel rotates. Thus, the flexure has a constantly wider spacing on the lead-in side, and a narrower spacing on the tape packing side. The spacing on the packing side is preferably equal to or less than the tape width.
Since the flexure rotates with the spool there is no relative motion between the tape and the packing device. Relative motion between the packing device and the tape has a tendency to generate debris, which can cause problems in a tape packing system. A preferred embodiment of the present innovations has no relative motion between the tape and the packing device. The packing device preferably spans the entire tape pack from the hub to the outer diameter, therefore no tracking mechanism is required. Additionally the packing device provides a gentle lead-in for the tape as it is fed onto the spool. Finally and foremost, the packing device provides a zero clearance fit for the tape which results in a smooth tape pack with no stagger wraps.
This new tape packing device minimizes the tape excursions that are currently seen in a tape drive. The reduced tape movement will result in lower tape guiding forces, less wear and easier track following. The innovative device is also direction independent, meaning the device will work in a variety of orientations, both loading and unloading tape, for example. All of the traits are required as we move forward with thinner tape and higher track densities.